Attenuation and diffusion in cancellous bone: implications for ultrasound-guided navigation in spine surgery
李索远 1李培洋 2邵维维 2焦阳 2李志强 1陆文佳 2崔崤峣 2范军界 3沈军 1刘新艳
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作者信息
1. 1南京医科大学附属苏州医院 苏州市立医院骨科，苏州 215002
2. 2中国科学院苏州生物医学工程技术研究所，苏州 215163
3. 3苏州市第九人民医院骨科，苏州 215000
折叠
摘要
目的 结合Micro-CT扫描数据了解椎体松质骨的声学特性，以此作为脊柱融合手术中超声导航后路椎弓根螺钉固定的理论依据。 方法 以2块牛脊椎松质骨块和2块人同种异体脊椎松质骨块模拟椎弓根螺钉通道内松质骨的情况，用Micro-CT扫描获得各骨标本的CT参数，用中心频率分别为2.2、2.5、3、12 MHz的无聚焦宽频换能器，分别对其进行超声透射实验，通过水听器检测穿过骨块样品的超声波振幅、声衰减和声速数据，计算骨块样品对不同频率超声波的衰减及声速影响。 结果 高密度人同种异体骨的骨体积分数和骨小梁数高于低密度人同种异体骨（均P<0.05），骨小梁分离度和结构模型指数低于低密度人同种异体骨（均P<0.05）。4块骨样本在4个不同频率下，超声波振幅随骨块厚度的增加而减小（均P<0.05），声衰减随骨块厚度的增加而增大（均P<0.05）。随着频率的增加，低频超声（2.2、2.5、3 MHz）下2 mm薄牛松质骨的声衰减逐渐减小[（r（牛骨1）=0.95，r（牛骨2）=0.89，均P<0.05]，4块骨样本声速均逐渐增大[r（牛骨1）=0.71，r（牛骨2）=0.81，r（高密度人同种异体骨）=0.35，r（低密度人同种异体骨）=0.61，均P<0.05]。牛松质骨中，在相同的低频超声（2.2、2.5、3 MHz）下，声速随骨厚度的增加而增加（均P<0.05）。 结论 松质骨骨块的CT参数特征和多种频率超声透射下的声学特性具有相关性，为超声导航系统的研发奠定了理论基础。 Objective To understand the acoustic profiles of vertebral cancellous bone in ultrasonography using data of Micro-CT scanning as the reference, so as to lay a theoretical foundation for ultrasound-guided posterior pedicle screw fixation in spinal fusion surgery. Methods Two cancellous bovine spinal bone blocks and two human cancellous allogeneic spinal bone blocks were used to simulate the cancellous bones along the pedicle screw channel. Each bone specimen was obtained of CT parameters on Micro-CT scanning, then subjected to ultrasound transmission measurement using an unfocused broadband transducer with central frequencies of 2.2 MHz, 2.5 MHz, 3 MHz, and 12 MHz, respectively. The acoustic amplitude, attenuation, and velocity of the ultrasound penetrating each bone specimen were captured by a hydrophone. Then the attenuation and impact on acoustic velocity of ultrasound by the bone specimens under different ultrasonic frequencies were calculated. Results High-density human allogeneic bone blocks presented higher bone volume fraction (BV/TV) and greater trabecular number (TB. N) (both P<0.05), lower trabecular separation and structural model index (bothP<0.05), compared with the low-density human allogeneic ones. For each of the 4 bone specimens under the 4 different frequencies, the ultrasound amplitudes decreased (allP<0.05) and the acoustic attenuation in creased (allP<0.05) with greater bone thickness. With rising frequency, a downward reduction in acoustic attenuation of low-frequency ultrasound (2.2 MHz, 2.5 MHz and 3 MHz) was noted inside the 2 mm thin cancellous bovine bone (r=0.95 for bovine bone block #1, r=0.89 for bovine bone block #2, both P<0.05), and an upward increase in acoustic velocity was noted inside all of the 4 bone blocks (r=0.71 for bovine bone block #1, r=0.81 for bovine bone block #2, r=0.35 for the high-density human allogeneic bone block, r=0.61 for the low density human allogeneic bone block, all P<0.05). In cancellous bovine bone blocks tested with any given low frequency of the ultrasound (2.2 MHz, 2.5 MHz, and 3 MHz), the acoustic velocity increased with greater bone thickness (allP<0.05) . Conclusion There is a correlation between CT parameter features of cancellous bone blocks and their acoustic profiles with ultrasound transmission at varying frequencies. This finding theoretically implies a foundation for development of ultrasound navigation systems.
Abstract
Objective To understand the acoustic profiles of vertebral cancellous bone in ultrasonography using data of Micro-CT scanning as the reference, so as to lay a theoretical foundation for ultrasound-guided posterior pedicle screw fixation in spinal fusion surgery. Methods Two cancellous bovine spinal bone blocks and two human cancellous allogeneic spinal bone blocks were used to simulate the cancellous bones along the pedicle screw channel. Each bone specimen was obtained of CT parameters on Micro-CT scanning, then subjected to ultrasound transmission measurement using an unfocused broadband transducer with central frequencies of 2.2 MHz, 2.5 MHz, 3 MHz, and 12 MHz, respectively. The acoustic amplitude, attenuation, and velocity of the ultrasound penetrating each bone specimen were captured by a hydrophone. Then the attenuation and impact on acoustic velocity of ultrasound by the bone specimens under different ultrasonic frequencies were calculated. Results High-density human allogeneic bone blocks presented higher bone volume fraction (BV/TV) and greater trabecular number (TB. N) (both P<0.05), lower trabecular separation and structural model index (bothP<0.05), compared with the low-density human allogeneic ones. For each of the 4 bone specimens under the 4 different frequencies, the ultrasound amplitudes decreased (allP<0.05) and the acoustic attenuation in creased (allP<0.05) with greater bone thickness. With rising frequency, a downward reduction in acoustic attenuation of low-frequency ultrasound (2.2 MHz, 2.5 MHz and 3 MHz) was noted inside the 2 mm thin cancellous bovine bone (r=0.95 for bovine bone block #1, r=0.89 for bovine bone block #2, both P<0.05), and an upward increase in acoustic velocity was noted inside all of the 4 bone blocks (r=0.71 for bovine bone block #1, r=0.81 for bovine bone block #2, r=0.35 for the high-density human allogeneic bone block, r=0.61 for the low density human allogeneic bone block, all P<0.05). In cancellous bovine bone blocks tested with any given low frequency of the ultrasound (2.2 MHz, 2.5 MHz, and 3 MHz), the acoustic velocity increased with greater bone thickness (allP<0.05) . Conclusion There is a correlation between CT parameter features of cancellous bone blocks and their acoustic profiles with ultrasound transmission at varying frequencies. This finding theoretically implies a foundation for development of ultrasound navigation systems.
关键词
超声检查/外科手术,计算机辅助/脊柱/松质骨
Key words
Ultrasonography/Surgery, computer-assisted/Spine/Cancellous bone
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